Robin Williams and Martha make chile-rubbed skirt steak tacos. Part 1.
On a work surface, crush garlic cloves using the flat side of a large knife; sprinkle with 1/2 teaspoon salt. Place the flat side of the knife blade on top of the garlic and salt; press firmly, pulling knife toward you. Repeat until a paste forms; transfer to a small bowl. Add chile powder, brown sugar, paprika, cumin, pepper, espresso, and remaining tablespoon salt; stir to combine.
Rub mixture all over skirt steak, and place in a large freezer bag to marinate for 30 minutes.
Preheat oven to 350 degrees. Wrap tortillas in parchment-paper-lined aluminum foil; while grilling steak, bake tortillas until warmed through, 10 to 15 minutes.
Preheat grill pan over high heat, or use an outdoor grill. Place steak on grill, and cook for 3 minutes per side for medium-rare. Let rest for 5 minutes before slicing. Serve thinly sliced steak in warmed tortillas; top with salsa, cilantro, cheese, sour cream, lettuce, and lime wedges, if desired.